Parking brake control system

ABSTRACT

A brake control device prevents movement of a vehicle, when an unsafe condition exists, by automatically applying the parking or other brake. The brake control system may prevent movement should the unsafe condition exist within, on or around, a towed device such as a trailer, a trailer-house or other recreational or non-recreational equipment. The brake control system may set a brake or parking device on the towed device whenever the towed device is disconnected from the motorized vehicle, or whenever equipment on the towed vehicle is extending outward or is otherwise un-stowed in a position unsafe for traveling, whether or not the towed vehicle is connected to the towing vehicle. Interface connections from the towed device to the powered towing vehicle may include wireless, electrical wire, fiber optics, analog, digital, or others. The preferred brake control system separates the controller and electronic operator switch and light/indicia that are handled or viewed by the driver from the actuation system that applies or locks the brakes, to use space more efficiently and to improve braking response time. These signals, such as electronic/electric/optic/wireless signals, travel between the cab and the brake management equipment to apply and release the brakes, and may be much more compact and more easily routed or transmitted through a vehicle than conventional air/hydraulic lines.

DESCRIPTION

[0001] This application claims priority of provisional applicationsSerial No. 60/297,682, filed Jun. 11, 2001, and Serial No. 60/322,371,filed Sep. 3, 2001, and this application is a continuation-in-part ofU.S. patent application Ser. No. 09/724,761, filed Nov. 28, 2000, whichis a continuation-in-part of U.S. patent application Ser. No.09/521,824, filed Mar. 9, 2000, (U.S. Pat. No. 6,322,161 issued Nov. 27,2001) entitled “Apparatus and Methods for Automatic Engagement andLocking of Vehicle Air Parking Brake,” which is a continuation-in-partof prior co-pending application Ser. No. 09/108,863, filed Jul. 1, 1998,and entitled “Automatic Air Parking Brake Lock,” which applications areherein incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention generally relates to braking systems for vehicles,such as buses, semi-tractor and trailers, and passenger vehicles. Moreparticularly, this invention relates to a control system forautomatically applying and maintaining a vehicle brake in the appliedcondition during times when it is unsafe or undesirable for the vehicleto move. The invention relates to a control system that may also lockthe brake when an unsafe condition begins after the parking brake hasbeen applied by the driver. Further, the invention relates to providingan electric/electronic switch for operation by the driver, replacingconventional manual hand and foot handles that must be pushed or pulledto set or release the parking brake. The invention also relates, in itspreferred embodiments, to providing a system that responds to varioussignals on or away from the vehicle to control a parking brake on aremote piece of equipment, such as on a trailer, camper, or other towedvehicle.

[0004] The invention may be adapted for use with brakes of varioustypes, for example, air parking brakes or mechanical parking brakes, orby adapting a hydraulic “application” brake, an air “application” brake,or an electric brake to serve as a parking brake. While the invention isprimarily focused on parking brake improvement, he invention may beused, in some embodiments, to apply and control application brakes.

[0005] The automatic application and locking of a vehicle brake may beactuated by signals from various sensors/switches inside and outside thevehicle. In a preferred embodiment, the invention relates to acontroller that automatically applies a parking brake when certainconditions are sensed in or around the vehicle, as long as the vehicleis not already moving at a speed that is judged as too fast for safeparking brake engagement and, preferably, as long as the sensedcondition signals are validated.

[0006] 2. Related Art

[0007] Commercial and public transportation vehicles typically utilizethe following types of conventional brakes:

[0008] 1) Air parking brakes utilize an air-controlled spring systemthat cooperates with the brake shoes of a vehicle's back wheels. Airparking brake systems exist in commonly-used commercial vehicles, suchas trucks, commercial buses, or school buses. The air parking brakesystem comprises an air source, the spring mechanism, and an air controlvalve called an “air loading valve” between the air source and thespring mechanism. The air loading valve is controlled only by a manualhandle, which is in the vehicle cab on the dashboard or in otherpositions accessible to the operator. The loading valve manual handleworks in a “Pull To Apply” and “Push To Release” manner. Pulling thehandle closes the air loading valve, whereby air pressure from the airsource is blocked and downstream air pressure is vented so that thesprings move to a position that applies the brake. Pushing the handleopens the air loading valve and closes the vent, whereby air is suppliedto the spring mechanism so that the springs move to a position thatreleases the brake.

[0009] The loading valve and its handle are located at the dashboard ofthe vehicle in the cab. The loading valve is very close to the driver,located just under the dashboard, with its handle protruding through thedashboard for access by the driver. Because of this location, the airlines to and from the loading valve travel typically from the rear ofthe vehicle all the way to the cab and into the space under thedashboard. This creates very long air lines, substantially the entirelength of the vehicle, and a very crowded situation under the dashboard.The air lines in large vehicles often are as long as 30 feet or more.

[0010] 2) Air application brakes, sometimes called “foundation brakes,”are the conventional means, in vehicles with air brakes, to slow andstop the vehicle, for example, during normal “stop and go” driving. The“air application brakes” are operated by a foot-actuated air controlvalve, which allows incremental application of the brakes depending onhow far the operator has pushed on the foot pedal.

[0011] 3) Mechanical parking brakes utilize a mechanical linkage or acable, to operatively connect a manual handle in the vehicle cab eitherto brake shoes at the rear wheels, or to external brake bands orinternal brake shoes working with a brake drum mounted on the driveline. The manual handle is typically either a pull-on hand-operatedhandle, or a push-on foot-operated pedal.

[0012] 4) Hydraulic “application” (or “foundation”) brakes are theconventional means, in vehicles with mechanical parking brakes, to slowand stop the vehicle during normal driving. A hydraulic applicationbrake system typically comprises a master brake cylinder for applyinghydraulic force to brake shoes at the wheels, and a manual foot-pedalfor actuating the master cylinder. Pushing on the brake pedal causes thebrake cylinder to increase the fluid pressure in the line to the brakeshoes at the wheel, which inhibits the rotation of the wheel to anincremental amount depending on how far the operator has pushed on thebrake pedal. When the pedal is released, the master cylinder retracts toreduce or eliminate the pressure in the brake line, disengaging thebrake shoe pads from contact with the brake drum and thereby allowingunhindered rotation of the wheel. Hydraulic application brakes are usedin most family cars, sport utility vehicles, pick-ups, vans, and largervehicles such as some school buses.

[0013] Crowded Equipment and Slow Operation

[0014] Conventional brake systems as described above involve manualcontrol/operation by a driver in the cab. Therefore, the conventionalsystems place substantial amounts of the equipment, for thecontrol/operation in the cab, typically at/in the dashboard or close tothe driver's hands or feet. This causes air lines, hydraulic lines, ormechanical linkages to be crowded into spaces in the cab, and the air,hydraulic lines, or cables to extend for long distances from the cab tothe brake mechanisms at the wheels. Not only does this result in crowdedor inconveniently-placed equipment and lines, but also in delayedactuation of brakes as the forces applied in the cab travel through longfluid lines to the vicinity of the brakes. For example, extra turns orsharper turns in an air parking brake line have been known to delay thebraking response, after the driver has moved his arm to pull the airloading valve handle. Such delays can be longer than acceptableaccording to safety requirement for commercial or passenger vehicles.

[0015] Regarding Vehicle Movement during Unsafe Conditions

[0016] Conditions may exist in or around a vehicle that make it unsafefor the vehicle to be in motion. Conventional safeguards against vehiclemovement when such a condition exists are inadequate, at least in partbecause the safeguards typically depend on the driver taking appropriateaction. This invention, without requiring driver action or involvement,automatically detects such conditions and automatically applies or locksthe brakes, thereby preventing potentially unsafe vehicle movement.

[0017] Vehicle movement when conditions exist that potentially make suchmovement unsafe are generally the result of (1) the driver's failure toproperly apply or engage the parking brake or application/foundationbrake system, (2) a third party's intentional release or interferencewith the parking brake, or (3) the driver's failure, whether intentionalor inadvertent, to detect and/or react to conditions which may makevehicle movement unsafe.

[0018] Examples of potentially dangerous conditions where movement of avehicle may be unsafe include but are not limited to the following:

[0019] A driver leaves a vehicle, or is otherwise not in a position tosafely operate the vehicle and fails to properly set the parking brake.

[0020] A driver attempts to put a vehicle in motion when people areattempting to enter or leaving the vehicle.

[0021] A driver attempts to put a vehicle in motion with a door open,wheel chair ramp in use, luggage compartment unlatched, or otherequipment similarly not in a safe operating mode.

[0022] A driver puts a vehicle in motion when an object is in closeproximity creating the potential for a collision. Examples include adriver failing to notice a pedestrian stepping in front of a bus or achild playing behind a parked car.

[0023] A driver's ability to recognize the existence of an unsafecondition is impaired. Examples include radio noise masking the warningwhistle of a train at a railroad crossing, a driver who is intoxicated,or a passenger who has not fastened safety restraints.

[0024] A vehicle that is approaching too close to an object, such as atruck backing up to a loading platform.

[0025] A vehicle with equipment that has failed or is not withinacceptable safety ranges, such as loss of tire or oil pressure.

[0026] An unauthorized driver is attempting to move or steal thevehicle.

[0027] Conventional “Push-Pull” Parking Brake Handles

[0028] Conventional parking brake systems include a manual handlemounted in the vehicle cab that applies the parking brake via mechanicallinkage between the manual handle and the brake or via mechanicallinkage between the manual handle and the air valve that actuates theair parking brake. In the case of most buses, this handle is ahand-operated push-pull loading valve handle extending from the airloading valve and through the dashboard. In the case of passengervehicles, this handle is a hand-operated lever located between the frontseats that is pulled up and rearward to apply the parking brake, andthen is pushed down, typically after pressing a button on the handle, torelease the brakes. Or, a foot-operated pedal is located near thedriver's compartment floor, and a hand-operated release handle is pulledto release the parking brake.

[0029] In any event, these structures may be called “mechanical hand orfoot handles” and they may also be termed “push-pull” handles, becausethey require significant manual strength and significant movement of thehand or foot to pull the handle enough to securely apply the brake.Then, it requires at least as much strength and movement of the hand orfoot to release the brake. Nearly every passenger car driver has been inthe position of struggling with the parking brake lever, foot pedal,and/or the brake release handle.

OBJECTS OF THE PRESENT INVENTION

[0030] There is a need for a versatile, reliable brake control systemthat is compatible with various types of existing brake technology.There is still a need for a comprehensive automatic brake control systemthat prevents vehicle movement during potentially unsafe conditions atvarious stations inside, outside, or around the vehicle, and to betterinform the vehicle operator of the potentially unsafe conditions. Thereis a need for a control system that automatically applies a brake and“locks” it in the “on” condition throughout the duration of potentiallyunsafe situations, and that also prevents automatic setting of the brakewhile the vehicle is traveling. There is a need for such a system thatvalidates signals coming to the controller to prevent noise, equipmentvibration, or other errors from applying the brake in error. There is aneed for such a control system that does not require driver action orinvolvement, but that does allow an authorized driver to override theautomatic systems under some circumstances.

[0031] There is a need for a more ergonomic parking brake system thatreplaces the clumsy and uncomfortable conventional brake handles with anelectric/electronic parking brake switch that is easily operated even byindividuals without great strength. There is a need for a controller andelectric/electronic switch combination that allows the driver to retaincontrol of the parking brake when none of the conditions exist that havebeen predetermined to be those that automatically apply the brake, andthat allows the driver to temporarily release the brake to allowmovement of the vehicle to a safe location for repair.

[0032] Also, there is a need for a brake control system that locates asmuch as possible of the brake control system equipment out of the caband closer to the brakes at the wheels. There is a need for a systemthat shortens the fluid lines in air and/or hydraulic systems and speedsup the braking response because of shorter lines and high-speed signalsand control.

SUMMARY OF THE INVENTION

[0033] The present invention is a parking brake control system thatautomatically detects potentially unsafe conditions and then enhancessafety by automatically applying a brake and maintaining the brake inthe applied position (“locking the brake”) and/or by controlling otherequipment. An object of the present invention is to provide an automaticcontrol system that requires little driver action or involvement, butthat allows the driver to more comfortably control the parking brakewhen there are no unsafe conditions sensed by the controller, or when anunsafe condition has applied the parking brake but the vehicle must bemoved to a safer location. An object of the invention is to enablesensors to detect the potentially unsafe conditions in or around thevehicle, to automatically alert the driver to the existence of suchconditions through visual and/ or audio or other means, and, whenappropriate, to automatically control the brakes and/or other equipment.Potentially dangerous conditions may include, for example: 1)equipment-related conditions such as a driver exiting the vehiclewithout applying the parking brake or without turning off the vehicle;operating a disabled person's lift; passengers entering and exiting thevehicle; engine or other vehicle malfunctions detected by diagnosticsensors; or a driver being distracted by radios, cell-phones, or monitorscreens; or 2) undesirable-or dangerous-driver-related conditions suchas a driver failing a breath alcohol test or an identity test.

[0034] An important object of the invention is to improve the ergonomicsof parking brake operation, by providing a parking brake driver's switchthat allows push-button operation rather than push-pull operation ofhandles mechanically linked to the parking brake. Other objects of theinvented control system may include preventing the brake from beingautomatically set while the vehicle is moving, and validating signals tothe controller so that noise and other false signals do not cause thebrake to be applied.

[0035] As a result of these and other objects of the invention, theinvented system allows a vehicle operator to focus more on safe drivingand vehicle operation, whether traveling or parked, and on thesurrounding conditions, rather than on repeated manual operation of theparking brake, and repeated checking of the parking brake handleposition. With fewer distractions, and fewer responsibilities foraccidental misuse or release of the parking brake, the vehicle operatorcan perform his/her job more safely. Further, elimination of thefrequent pulling and pushing of the parking brake manual handle mayreduce carpal tunnel syndrome or other discomforts and injuries inveteran drivers.

[0036] The invented control system comprises a “management mechanism”for applying a brake, a controller with the logic that decides when thebrake should be applied and that electronically actuates the managementsystem to apply the brake, and various circuits and sensors for linkingthe controller to the various stations inside, outside, and around thevehicle. The invented controller may be used with a variety of existingbrake systems, by adapting the management mechanism for the particulartype of brake system being used.

[0037] In an air brake system, the management mechanism is preferably avented solenoid valve that replaces the conventional loading valve inthe air line to the spring mechanism. The solenoid valve cuts off theair supply and vents the air line to release a piston that normallycounteracts a spring mechanism, so that the spring mechanism applies thebrakes.

[0038] When adapted for the hydraulic application brake system, theinvented management mechanism may be of two general types: 1) an air,hydraulic-oil, spring, or other actuator that causes the master cylinderto apply the brake; or 2) a pressure generator that is “inserted”between the master cylinder and the brake mechanism and that createspressure in the brake fluid line to apply the brake. After either typeof management system is installed in a hydraulic brake system, theadapted brake system then serves double duty as a “hydraulic parkingbrake” as well as a hydraulic application brake. The preferredmanagement mechanism adapted for a hydraulic system is of the first typelisted above, and comprises a piston or spring that powers a secondarypiston rod to move the piston in a master cylinder to apply the brakes.In the case of a spring-actuated secondary piston rod, a release unitsuch as a piston may be controlled to counteract the spring forreleasing the brakes.

[0039] When adapted for the mechanical parking brake system (eitherwheel brakes or drive line brakes), the invented management mechanismoperatively connects to the mechanical brake linkage, such as a brakecable. The management mechanism may be, for example, apparatus forair-actuation, hydraulic-oil actuation, spring-actuation orelectric-actuation of the mechanical brake linkage.

[0040] The various circuits, sensors, and switches included in theinvented control system automatically 1) sense conditions, of one ormore “stations” in or around the vehicle, that are potentially dangerousif the vehicle moves and 2) automatically signal the controller, whichdecides whether or not to “trip” the management mechanism to apply thebrakes. Such “stations” may be vehicle components, such as the ignitionsystem, the vehicle main door and/or an emergency door, a wheelchairlift, a dump truck bed, a delivery vehicle door, a trailer, a craneboom, outrigger, seat belts, a pressure-sensing operator's seat sensor,tire pressure sensor, engine oil pressure sensor, emissions sensor, airbag sensor, or other vehicle or engine diagnostic sensors that sense andsignal the controller when conditions are outside of the normaloperating range. Other “stations” may include equipment, objects, orlocation of people outside a vehicle, for example, that are positionedtoo near or moving too near to the vehicle in a street, parking lot,loading dock or warehouse. Other “stations” may include test units fordriver condition or desirability, such as a breath analyzer, a voiceanalyzer, or an access-code key-pad, for example.

[0041] In general, signals from the various “stations” inside, outside,or around the vehicle to the controller are created by sensors orswitches being actuated by the movement of, or the position of,equipment or people, and this actuation signaling the controller, forexample, via sensor circuits or other electric or electronic means orother transmission. In some cases, actuation of the sensor or switch ata particular station comprises interruption, either the positive side orthe negative/ground side, of the controller circuit including theparticular sensor or switch. Various means of switching/sensing may beused, for example, conventional electrical contact, sound-switching,light-emitting-switching, magnetic-switching, fluid, pressure, radar,sonar, microwave, or any other conceivable switching or sensing. When asensor or switch, or, alternatively, when a certain combination ofsensors or switches, is actuated, and the controller decides thatconditions are appropriate, the controller “trips” the managementmechanism and the management mechanism applies the brakes. As long asthe condition causing the “trip” persists, the brakes remain locked inthe applied condition in most circumstances. For example, a switch maybe operatively connected to a handicapped lift system, and the switchmay be electrically/electronically connected to the invented controller,so that using the lift opens a circuit to the controller, which tripsthe management mechanism to apply and lock the brakes. Once the liftsystem is not in use, the driver may release the brake. Likewise, aswitch may be operatively connected to a door, and the door switch maybe electrically/electronically connected to the invented controller, sothat opening the door breaks its sensor circuit and trips the managementmechanism to apply and lock the brakes. Once the door is closed, thedriver may release the brakes. For simplicity hereafter and in theclaims, the term “sensor” may be used to indicate any sensor or switchat a “station” that is actuated by conditions at the station to signalthe controller.

[0042] A preferred feature of the preferred invented control system isthat loss of power to the management mechanism causes it to apply andlock the brake. In the especially-preferred embodiments, any time thatpower is removed from the control module (the “controller”), power isalso removed from the management mechanism and the brakes are applied.The positive power input for the preferred controller is activated byeither direct or indirect operation of the ignition switch of thevehicle. Therefore, turning the vehicle ignition to the “OFF” positiondeactivates the controller and the management mechanism to apply thebrakes.

[0043] The preferred brake control system also includes a sensor andlogic for preventing automatic application of the brake if the vehicleis in motion above a certain speed. This feature of the invented controlsystem may be adapted to interface and cooperate with various designs ofspeedometers, such as magnetic, electrical, or electronic sensor types,or other means for measuring vehicle motion or speed. For example, aconventional speedometer magnetic pick-up may be used to signal thecontroller for this purpose.

[0044] The preferred brake control system also includes features thatimprove operability in substantially all vehicles, specifically, asignal qualifying circuit and noise suppression functions. The preferredsignal qualifying circuit detects the presence of a constant voltagemaintained for a minimum duration of time, in order to verify that asignal to the controller is “real,” that is, it is not a signal createdby a jiggling of a switch, electric noise or other false signals.Alternatively, a qualifying circuit may also use other measurements,such as frequency, to verify true signals. The noise suppressionfunctions may be affected by a combination of various transientsuppression inductors, capacitors, diode and surge protectors.

[0045] The preferred operator switch is an electric/electronic switchthat is used in various scenarios. First, the operator may apply theparking brake when desired, at times when it is conventional to applythe brake, such as in a parking lot, with the main difference being thatthe operator needs only to touch the “apply” button of the switch ratherthan pulling a hand-handle or pushing a foot pedal. Secondly, after theoperator has applied the brake or the controller has automaticallyapplied the brake in response to one or more sensors signaling an unsafecondition, the operator may then use the operator push-button switch torelease the parking brake as long as there are no unsafe conditionsstill being signaled. Thirdly, the preferred brake control systemincludes a brake-releasing override system to override the controller'sapplication of the brakes, during emergencies and/or at the driver'sdiscretion. For example, if the invented controller applies and locksthe brakes when the vehicle is still in traffic, the driver may use thebrake-releasing override to release the brake for enough time to movethe vehicle to the side of the road. The manual brake-releasing overridemay include, for example, the driver pushing and holding the releasebutton on the operator switch while driving the vehicle to safety. Thisway the driver must use one hand to steer while keeping the other handon the release button, applying constant pressure on the release button.A driver is unlikely, therefore, to use this override except inemergencies.

[0046] Some embodiments of the brake control system separate thecontroller system from the actuation system, to use space moreefficiently and to improve response time. The invention maintains allequipment that must be accessed by the driver in a convenient andsafely-visible position in the cab, while placing “remotely” theequipment that mechanically or fluidly communicates with the brakes.More specifically, the preferred “controller system” comprises theoperator switch, lights or other indicators, and a controller, and islocated at or near the cab, in a position where the driver may accessthe operator switches and see the indicators. The controller system maybe compact, especially if the controller is solid-state and/ormicroprocessor-based. The switching and indicator lights may be small aswell, so that the overall size of the controller system takes up only afew cubic inches of volume at/under the dashboard. The controller,operator switch and indicator lights may be provided in a single housingthat may be installed at the dashboard.

[0047] In such a remote system, the preferred “actuation system” (alsocalled herein “management system”) is located more distantly, preferablyaway from the dashboard. Between the controller system and themanagement system are signal means such as electrical connections, dataconnections, fiber optics, wired or wireless communications and/or othermeans for sending actuating signals from the controller to themanagement system to apply the brakes or release the brakes. Thus,electronic/electric/optic/wireless or other signaling means travelsbetween the cab and the brake management equipment but these signalingmeans are much more compact and more easily routed or transmittedthrough a vehicle than the conventional air/hydraulic lines. Mostpreferably, some or all of the communication, between the motorizedvehicle and the towed vehicle being pulled by the motorized vehicle,regarding the parking brake is done by wireless means. That is, thepreferred signals from sensors on the towed vehicle to the controller inthe cab are preferably all sent by wireless means, and the commands fromthe controller to the management system on the towed vehicle arepreferably all sent by wireless means. This way, regarding the parkingbrake system according to this invention, the driver does not have tostruggle with repeated connection and disconnection of wired or otherhard connections between the vehicle cab and the trailer or other towedvehicle, greatly improving the reliability and convenience of theparking brake system for the towed vehicle.

[0048] Preferred embodiments of the remote system include a controllerat the dashboard, and a brake management system located at or near thefirewall of the engine compartment, or even further from the cab of thevehicle in preferred positions near the brakes, axle, ordifferential/transfer case. In towed vehicle embodiments, the controllersystem is located near the driver in the towing vehicle, and themanagement system is location near the brakes and wheels in the towedvehicle. In air parking brakes, for example, these invented arrangementsmay allow a substantial reduction in the length of the parking brake airlines, and may move the brake management system and air lines out fromunder the dashboard to a less crowded location.

[0049] In a first preferred embodiment, the controller system is locatedunder the dashboard very near the dashboard surfaces.Electrical/electronic connections are supplied from the controllersystem to the management system that is at the firewall of the vehicleengine compartment. Fluid line connectors extend from the managementsystem through ports in the firewall. The fluid lines, therefore, needonly extend to the firewall and not into the cab underneath thedashboard, and the space underneath the dash is therefore not clutteredand crowded with air lines.

[0050] In a second embodiment, the controller system is again locatedunder the dashboard very near the dashboard surfaces.Electrical/electronic connections, fiber optics, wireless signals, orother signaling means are supplied from the controller system to themanagement system that is near the brakes themselves, preferably at theaxle or transfer case at the axle. Thus, the signaling means extend thelong distance from the cab to, for example, the rear axle for engagementof the rear brakes.

[0051] Another benefit of the remote system may be that it may allow theair solenoid valve to be combined in a housing with other air valvesneeded for vehicle operation.

[0052] In vehicles containing an air parking brake, the managementsystem comprises a vented solenoid valve, replacing the conventionalloading valve in the air line to the spring mechanism. The ventedsolenoid valve, however, is not placed where the conventional loadingvalve has been placed for years (under the dash) but rather is placed adistance from the dashboard, for example, at the fire wall or, morepreferably, at the axle or transfer case near the wheels and theirbrakes. Such a “remote” system will allow bus air lines, for example, tobe shortened from 30+ feet to 5 feet or less.

[0053] In other types of brake systems, again the controller system(controller, and its associated equipment, the manual switch andindicator(s)), are preferably placed at the dashboard or near thedriver's hands or feet, and the management system is distanced from thecontroller and associated equipment. The various brake systems andvehicle manufacturers will have their preferred arrangements, but thegeneral rule of separating the controller/manual switch/indicator fromthe management system will provide much more flexibility and options forbetter vehicle and cab design and for faster brake actuation.Preferably, the management system is distanced at least 2-4 feet fromthe controller system, and, more preferably, from 5-30 feet from thecontroller, depending whether the management system is actuating orcontrolling the parking brake, or front or rear foundation brakes.

[0054] Optionally, the brake control system may automatically apply thebrakes according the invention in response to signals relatively farfrom the vehicle and the controller, instead of from signals on thevehicle or on the towed vehicle. For example, the brake control systemmay be adapted to receive signals transmitted from trains or other largeequipment that indicate that the train/equipment is approaching. In thecase of a train, all trains may transmit on a particular frequency thatis set aside for rail road crossing safety, so that, when thecontroller's receiver picks up that signal from any train, thecontroller automatically triggers the management system to apply thebrake. The invented brake control system could be adapted so that thesignal is detected only within 50 feet, or even a shorter distance suchas 10 feet, to prevent the unnecessary and confusing result of vehiclesbeing braked when they drive along-side a rail-road but are not indanger. When a vehicle is within 10 feet of a moving train, however, theparking brake should be applied generally under any circumstance. Thebrake control system could be adapted to even bypass the vehicle motionoverride system, to prevent vehicles from racing across the crossing infront of the train. Also, the validation time for a train signal couldbe set very low, for example, 0.5 second. Alternatively, a train warningsystem could be set up so that a satellite/GPS system calculates that avehicle is dangerously close to a train or other large moving equipmentand sends a signal to the brake control system to apply the brakes ofthat particular vehicle. Such rail-road crossing systems coulddrastically cut the number of deaths per year from car-train andbus-train accidents.

[0055] Another optional but beneficial feature of some embodiments ofthe invention is an adaptation that allows the parking brake to beautomatically applied slightly before the vehicle transmission is put in“park.” Such a system could time the application of the brakes so thatthe wheels, and therefore the vehicle, are truly stopped and kept frommoving a second or fraction of a second before the pawl moves into placein its “parking” location of the transmission. This prevents the pawlfrom actually being the member that stops the vehicle's motion, andprevents the situation in which a driver “throws” the transmission into“park” before motion is completely stopped, and either damages the pawlor wedges the pawl in a position with too much force against it. Thus,this invented features may prevent damage to the pawl, to thetransmission, and may especially prevent the situation in which the pawlcannot be removed from the park location (shifting from park is notpossible) because the pawl is wedged/jammed into place with too muchforce against it (caused by transmission movement after the pawl movesinto place) and cannot be moved. Such a system is made possible andpractical when parking brake actuation is made to have little lag, delaytime, as is the case with the invented “remote” management system andits short fluid lines. Preferably, the invented brake control systemapplies the parking brake immediately before the pawl moves into parkposition in the transmission, which means that the parking brake istypically completely applied within less than 1 second, and more likely,less than 0.5 seconds, before the pawl is in the park position in thetransmission.

BRIEF DESCRIPTION OF THE DRAWINGS

[0056]FIG. 1 is a schematic drawing of a conventional bus air parkingbrake system, in which an air loading valve with a manual handle is atthe dashboard of a vehicle, and the air lines extend on the order of 30feet to the parking brakes at the rear of the vehicle.

[0057]FIG. 2 is a schematic drawing of a prior art loading valve andmechanical handle configuration for a bus parking brake.

[0058]FIG. 3 is a schematic drawing of one embodiment of the inventedbrake control system, which comprises a controller system in a vehiclecab and a management system over the brakes and wheels.

[0059]FIG. 4 is a schematic drawing of a first preferred embodiment ofthe invented remote system for brake control, showing air line portsthat may extend through the fire wall.

[0060]FIG. 5 is a schematic drawing of a second preferred embodiment ofthe invented remote system for brake control.

[0061]FIGS. 6 and 7 illustrate remote systems wherein equipment or tireconditions on a towed trailer cause trailer brake actuation.

[0062]FIG. 8 is a schematic view of an embodiment in which a vehicle isbraking because it is approaching a moving train.

[0063]FIG. 9 is one embodiment of an operator switch according to theinvention.

[0064]FIG. 10 is another embodiment of an operator switch according tothe invention.

[0065]FIG. 11 is an embodiment of a controller system which combines acontroller in a single unit with an operator switch.

DETAILED DESCRIPTION OF THE INVENTION

[0066] Referring to the Figures, there are shown prior art systems andseveral, but not the only, embodiments of the invented brake controlsystem. FIGS. 1 and 2 illustrates schematics of one type of bus airparking brake system, including the conventional loading valve 6 thathas been used for many years, closely underneath the dashboard so thatthe loading valve handle may extend through the dashboard to be reachedby the driver. Air lines in the conventional system extend all the wayto the spring units at the wheels, which may involve many feet of airlines and, hence, delays in brake actuation and increased possibility ofdamage of the air lines. This conventional placement of the loadingvalve (also called “push-pull” or “PP” valve) and its manual handleresult in the air lines 4, 12, in effect, extending through the vehiclecab because they must come within a few inches of the dashboard.

[0067] In FIG. 1 is shown schematically the invented brake controlsystem that may replace conventional systems such as the old loadingvalve 6, to improve vehicle safety by providing an automatic parkingbrake feature and to improve the ergonomics of operating a parkingbrake. In FIG. 1, the dotted line around the conventional loading valvedenotes that it may be replaced with the preferred invented brakecontrol system, so that, instead of a loading valve with its push-pullhandle, the invented control system is used to apply and control theparking brake. As suggested in FIG. 3, the invented control systempreferably comprises a controller 162, an operator switch 163, and wiredor wireless connections to management system and to the sensors thatsignal the controller.

[0068] In the preferred embodiment, as illustrated in FIGS. 4 and 5, acontroller is supplied, preferably with a manual operator switch foremergencies and indicator lights, on or directly underneath thedashboard. From the controller are signal lines (eitherelectronic/electric, fiber optic, or wireless communication) butpreferably not air lines. The signal line(s) extend or transmit to aremote management mechanism or “management system” that is closer to thebrakes being controlled. At a minimum, the management system is locatedaway from the dashboard near the firewall, as in FIG. 4. In FIG. 4, themanagement mechanism is placed on the firewall, with ports accepting theair lines. Here, the air lines do not extend to the dashboard, nor intothe cab, so crowding under the dashboard is prevented.

[0069] More preferably, and especially for towed vehicles, themanagement system is located far away from the dashboard and thecontroller, for example, very distant from the dashboard, preferably ator near the axle of the wheels being slowed or stopped by the brakes, asin FIG. 5. The management mechanism may be a solenoid air valve at ornear the differential or transfer case. In such a case, the signals orsignal lines travel all the way from the control system in the cab, butthe air lines do not. This way, air lines only a few feet long (forexample, about 2-4 feet long, rather than 20-30 feet) may be installed,thus, saving on equipment, on possibly-damaged or leaking lines, and ondelay in braking caused by turns or bends or extra length in air lines.The preferred “actuation system” (also called herein “managementsystem”) is located away from the dashboard and most preferably withinabout 2-5 feet of the brakes at the wheels. This way, airlines orhydraulic lines in a hydraulic brake system should preferably each beless than about 5 feet long.

[0070] An adaptation for the management unit at the very distantlocation or at any non-cab location is to have a heat source or otheradaptation to prevent any freezing/icing of the valve or the lines inthe valve, and/or to prevent freezing of the parking brake in the onposition. Because the solenoid valve is not in the heated cab duringcold weather, a heat source may be supplied. This may be done by sizingthe solenoid coil sufficiently large and of such a design that, becauseelectricity goes through it during normal operation of the vehicle,there is enough resistance that heat is produced in sufficient quantityto heat the valve and prevent freeze-up. Other heating systems may alsobe used to prevent brake freeze-up, such as heating at the wheels.

[0071] Especially-preferred embodiments of the invention relate toparking brake systems for vehicles that are towed by a powered vehicle,which may be recreational vehicles such as 5^(th)-wheels, trailers oftractor-trailer combinations, or other typically non-powered vehicles.For convenience, we refer hereafter to these units as “trailers.” Moreparticularly, the invented control system automatically applies and“locks” a brake on the trailer in an applied condition during times whenit is not safe for the trailer to move, that is, when it is not safe forthe driver to hook up with the trailer and pull away. The invention mayprevent much damage of property, both the trailer and bridges,buildings, or other property. Also, this invention will help preventunsafe use of the trailer or “run-away” or stolen trailers or equipment.Particularly, the invented brake control will signal and lock/apply thetrailer brake(s) when an extension such as a slide-out or stabilizer isextending out to the side or down to the ground, respectively. Or, thebrake will automatically be applied or locked on when entry steps arenot stowed, when tire pressure is low, when stoves or water heaters arenot in a safe travel arrangement, when a hitch or connection to thetowing vehicle not properly set, or some other piece of equipment is notin proper position for movement.

[0072] The invented brake control system may include a controlleraccording to the above-cited patent applications, and the controller maybe on either the towing vehicle or the trailer. The controller receivessignals of unsafe conditions in the trailer via circuits or othernon-wire signal means, processes the signals and actuates the brakemanagement on the vehicle.

[0073] Preferably, the power source for the controller is power from thetowing vehicle or from the power source on the trailer, if there is one.The invention may be adapted for either manual brake, air brakes, orhydraulic brakes on the trailer. The invented system preferably does notadd a power source to the trailer, except in some instances amechanical, spring or lever operated actuator for a brake for instanceswhere the power source in the towing vehicle is likely to bedisconnected from the towed vehicle or for instances in which thetrailer normally only has a manual brake. The invented system preferablydoes not interfere with the normal braking action of the towed device orthe towing vehicle when in motion and in safe operating condition.

[0074] Examples of implementation are:

[0075] When towing vehicles is hooked up to the trailer, the inventedsystem will keep the brakes on the trailer applied if any “unsafesignals” are fed from the trailer to the invented controller—that is,for example, if any extensions are still out, steps are down, otherequipment not properly stowed or positioned, or tire pressure notadequately. In such an implementation, power may be supplied to thecontroller by the towing vehicle, and the normal brake system of thetrailer may be adapted to cooperate with the controller. When the towingvehicle and trailer are hooked up together, the brake should be operableby the normal means, for example, air or hydraulic means, so that a newbrake mechanism need not be added to the trailer.

[0076] The invention may also be adapted for implementations where thepower source is cut off, that is, where the towing vehicle isdisconnected and the trailer does not have its own power source, anddoes not have its own air or hydraulic fluid source for the brakes. Insuch examples, the invention may include a spring-actuated electricbrake or other spring-actuated brake, so that the brake is not releaseduntil the towing vehicle is reconnected to the trailer and until no“unsafe signals” are received by the controller. In other words, thistype of embodiment of the invention may be in safe mode each time thetrailer is disconnected from its towing vehicle and also when anyextensions are out, any equipment un-stowed, tire pressure low, etc..The invention in these cases, therefore, would include the addition tothe trailer of a brake actuator having a mechanical component, such as aspring-actuated brake or manual-actuated brake, to allow actuation(continual actuation) of the trailer brake until all the safetyconditions are met.

[0077]FIG. 6 is a side schematic view of a towing vehicle and arecreational vehicle with one embodiment of the invention, with thecontroller in the towing vehicle. In FIG. 6, a “slideout” 50 of arecreational vehicle is sensed as being out, a stabilizer 52 is down,and a tire is sensed 54 as being at low pressure, so the controller isapplying the trailer brake. FIG. 7 is a side schematic view of a vehicleand trailer with the controller in the trailer, and with unsafe signalsfrom tires and steps causing the controller to apply the brakes of thetrailer.

[0078]FIG. 8 illustrates vehicles 60, 60′ that were approaching a movingtrain 70, but that are now braked because of a signal from the train tothe invented controller.

[0079] Solid-state brake control systems are especially preferredembodiments of the invention, as they may include many safety featuresand many data ports for sensing conditions at various stations in andaround the vehicle. An example of a solid-state brake control system,according to the invention, includes a solenoid valve, a solid-statecontroller, and an operator control switch mounted in a chosenconvenient position. These three main components are operatively andelectrically/ electronically connected to perform the required anddesired methods of applying and locking a parking brake. Preferably, theinvented control system should be compliant with all required FederalMotor Vehicle Safety Standards and compatible with the existing brakeand ABS brake systems. One solid-state brake control system is describedbelow:

[0080] Given the description and drawings contained herein, one skilledin the art may see how a brake control system including a solenoid valveunit 160 with a solid-state electronic controller 162 (FIG. 10) may haveadvantages in size, reliability, versatility, and adaptability to manydifferent vehicles. The controller 162 is designed to receive andprocess the signals from a plurality of sensors/switches at the variousstations, and, appropriate, to signal the management systems that manageeither air, brake fluid, hydraulic fluid, mechanical, or electricdevices to cause application of the brakes. For example, in air parkingbrake applications, the management mechanism is a solenoid valve thatcloses and vents; in hydraulic brake applications, the managementmechanism is the pressure generator and associated valving that isinserted between the master cylinder and the brake mechanism, or anactuator that causes the master cylinder to create pressure; or, in amechanical brake application, the management mechanism is an air,hydraulic, spring, or other unit that connects to and operates themechanical linkage to the brake mechanism.

[0081] The controller 162 is operatively, and preferably alsophysically, attached to the management mechanism. Alternatively, thecontroller 162, solenoid 160, and operator switch 163 may be separatestructures electrically/electronically connected.

[0082] The controller 162 may be a printed circuit board, which mayinclude some imbedded microprocessor chip(s), or may be a substantiallymicroprocessor design. The printed circuit board and/or microprocessorsmay be manufactured according to conventional circuit board and/or chipmanufacturing techniques once the invented apparatus, circuits, andmethods described and drawn herein are understood. Optionally, thecontroller may include memory to record the control events that takeplace over time, for example, to create a safety record or operatordriving performance record.

[0083] Preferably, the operator switch includes manual switch buttonsthat are referred to herein and in the drawings as either “actuate” and“dictate” switches or buttons, or “brake locked” and “brake released”switches or button. Preferably, the operator switch also includesindicator lights and labels for each station, indicating which stationis causing the engagement of the brakes. See, for example, the operatorswitches of FIGS. 9 and 10. FIG. 9 illustrates an operator switch 200which replaces the conventional manual brake knob that bus operatorshave used for so long. FIG. 10 illustrates a more complete operatorswitch 210, of the type that may include, for example, rows of red LEDlights 211 labeled “Door,” “Lift,” “PTO/Aux,” “Spare,” etc, positionednear the “activate 212 deactivate 213” switch with red indicator 171 andgreen indicator 173, which switch is discussed below, and an optionaltrailer brake control 215 and red and green indicator lights 216, 217.Optionally, liquid crystal, TV, or monitor technology may be used toprovide text, symbolic, or other indicia or visual representations toeducate the driver or other observer about the existing conditions.

[0084] Optionally, the controller 162 may be placed inside the operatorswitch body, providing a compact combination controller-switch-valveunit as is illustrated in FIG. 11. The combined unit shown in FIG. 11includes operator switch 200 which encloses a microprocessor controller162 inside its body. The switch 200 operatively connects to asolenoid-controlled air valve (solenoid portion 220 and air valvingportion 230). A low pressure switch 240 is shown attached to the side ofthe air valving portion 230.

[0085] Preferably included in the solid-state embodiment are thefollowing features, described for an air parking brake embodiment:

[0086] Solenoid Operation

[0087] 1. The solenoid employed in this design places the vehicleair-disengaged/spring-engaged parking brakes in the applied positionwhenever the solenoid is not energized, that is, when current is notpassing through the solenoid coil from the control unit.

[0088] 2. The controller is designed so that, upon the vehicle ignitionbeing turned on, the controller automatically powers up in a state inwhich the brakes are locked. Thus, the system does not require anymanual application of the brakes by the operator when the vehicle isfirst started. A red indicator light 171 shows that the brake is appliedwhen the vehicle starts up.

[0089] 3. Releasing the brake may be done by momentarily placing the“activate/deactivate” momentary switch 175, which may be located on thecombined switch/display box 163, in the activate position. This causesthe electronic control circuit to latch DC ground to one side of the airbrake control solenoid. The other side of the solenoid is electricallywired to the +12 DC side of the vehicle's electrical system. It may benoted that alternative embodiments may be adapted to other than a 12volt system.

[0090] 4. Manual or other release of the brake may not be done, and thered indicator will continue to flash, if the vehicle's supply airpressure is less than a predetermined set point pressure. (See LowPressure Detection, below).

[0091] 5. This latching energizes the solenoid and releases the brakes.This action is indicated by the controller turning off the red indicatorlight and turning on a green indicator light 173. This latching actionreleases the vehicle parking brakes for normal usage.

[0092] 6. As long as the solenoid remains latched, the brakes willremain in their normal operating state. This condition will remain thisway until the controller is electronically or manually reset(de-energized) in one of the following manners:

[0093] a. Manually placing the “activate/deactivate” switch into the“deactivate” position; in this case, deactivation takes place nearlyinstantly. This places +12 v on a controller connector input pin thatinstantly resets the control circuit and de-energizes the solenoid. Thisfunction is not over-ridden by the speedometer input function; it isactive whether or not the vehicle is stopped or in motion. In otherwords, the operator can manually apply the brakes whether or not thevehicle is in motion, giving the operator control in an emergency.

[0094] b. If the low air pressure switch closes.

[0095] c. If a door switch, that has its contacts normally open, closes(because the door is opened). This control input is only active when thevehicle is not in motion.

[0096] d. Optionally, if any other stations to which a particularcontroller is operatively connected signal the controller that acondition exists that warrants application of the brakes. For example,such stations as a “PTO/aux.” (power take off/auxiliary) switch, awheelchair lift switch, or other described elsewhere in thisDescription.

[0097] Preferably, in the case of the above operations, the controlleris designed so that the signals of any of these sensors/switches mustremain non-interrupted for predetermined amount of time, for example, inthe range of 0.5 to 2 seconds, and more preferably in the range of 0.5to 1.25 seconds, to validate their operation before the controllerapplies the brakes. Once the brakes are applied because of thesesignals, the brakes remain applied in the locked state until thepotentially unsafe condition has been eliminated and the brakes are thenreleased by the driver releasing the brakes with his/her manual controlswitch. If the potentially unsafe condition has not been eliminated, thedriver, in an emergency, the driver may manually release the brake byusing the manual brake-releasing override for a short period of time tomove the vehicle to safety.

[0098] More specifically, in the especially-preferred control system:

[0099] Low Pressure Detection

[0100] The especially-preferred controller is set up to detect theopening of a normally closed pressure switch. This pressure switch, setto open when the air pressure falls below the pressure set point(typically approximately 35 pounds per square inch) is placed in serieswith the control system solenoid coil. Thus, it may be seen thatpreferably only the electronic controller and the pressure switchcontrol the flow of electrical current to the solenoid. When the airpressure falls below approximately 35 psi, and this pressure switchopens, current is broken to the control solenoid and this action appliesthe air brakes in the locked position. The controller senses this andresponds by resetting all of its control latches such that the brakescan not be released until the air pressure is restored to over 35 psi.

[0101] Likewise, the controller also senses whether or not this airpressure sensor is open or closed when the vehicle is first started. Ifthe air pressure is below 35 psi on start up, the controller unit willnot allow any type of brake release, including the operators manualrelease switch, until 35 psi air pressure exists.

[0102] Initial Power Up

[0103] Specifically, upon application of the vehicle DC power to thepreferred controller, the following functions take place, regardless ofthe state of any of the sensor inputs to the controller.

[0104] (1) Capacitors begin charging throughout the entire controller,two of which are specifically placed in series with Resistors to performthese two initial functions:

[0105] (a) Power On Reset pulse to initiate the start up latches intheir reset mode the solenoid latch circuit;

[0106] (b) A pulse that sets the second latch to reinforce the cutoffstate of the first latch.

[0107] (2) As a result of the action of the two above noted pulses, thesystem is automatically forced into the “Brakes Locked” state. The onlymeans of releasing it from this state is with the operator manualbrake-releasing override but that too is conditional to operating airpressure being above a set minimum value. The controller responds asfollows:

[0108] (a) If the air pressure is below 35 lb. per square inch, all airbrake solenoid release functions are blocked by the control unit.Furthermore, when the air pressure is below this 35 psi, a set ofcontacts, wired in series with the power leads to the air brakesolenoid, are in the open position, further preventing current flow inthe solenoid. This state will remain in effect until such time as theair pressure has exceeded the 35 psi minimum and has closed the pressureswitch that is in series with the power lead going to the solenoid.

[0109] The operator of the vehicle is alerted to this low pressurecondition by the flashing state of the red light emitting diode lamplocated in the operator's switch and indicator housing. This indicatorlamp remains in flashing mode, of approximately 4 Hertz andapproximately a 50% on/off duty cycle, as long as the air pressure isless than 35 psi. Once the air pressure is up to correct level, the lampceases to flash and switches to a steady ON state, notifying theoperator that they can now release the air brakes.

[0110] (b) If the air pressure is above the 35 psi minimum after initialpower up of the controller, the red LED indicator lamp will initiallyturn on in the steady state, notifying the operator that working airpressure exists in the air brake system. The system will now permitrelease of the air brakes, but only by the operator release switch. Whenthe operator depresses and releases his manual release switch, the twolatches, that are used to initially place the brakes in the lockedposition on power up, are then set in the “brakes released mode”, andpower is supplied to the air brake control solenoid by a translatorswitch within the controller. In general, the air brake solenoid allowsthe brakes to be released only when power is applied to it. Any eventthat results in interruption of the current path to or from the solenoidwill result in the brakes being locked.

[0111] Sensors Operations

[0112] The especially-preferred controller makes use of two differenttypes of sensor input lines.

[0113] (1) Six input lines that are active when connected to vehiclenegative ground side of its electrical system;

[0114] (2) Two dedicated function (passenger door) sensors, one that isactive when connected to the positive side of the electrical system, theother active when connected to the negative side of the vehicleelectrical system. These two inputs are unique from the other six inputlines in that, upon their release from their respective active sides,they cause the air brake to automatically release, whereas all theothers require that the operator depress and release the manual releaseswitch.

[0115] The system is not limited to these six negatively active inputsor just the one positively active door input. An infinite number ofadditional lines of the same type may be connected to either or all ofthem, provided caution is exercised to prevent dead short current loopson negative inputs and that one uses input codes on the positive doorinput to isolate the positive inputs form one another.

[0116] Sensor Signal Validation Circuit

[0117] To provide a measure of protection against false setting of thebrakes caused by noise, a “loose” switch, a defective switch, and etc.,a circuit has been included in the controller that requires that asensor signal be present, without interruption, for a predeterminedminimum time, for example, a minimum time set between 0.5 to 1.25seconds, before it will recognize it a valid signal and latch thebrakes. Thus, if the minimum time is set at 1 second, the signal must bepresent without interruption for at least 1 second before it isrecognized as a valid signal.

[0118] This delay time is common to all sensor inputs except the lowpressure sensor, which is instantaneous and can only exist when thepressure switch has indeed opened from lack of pressure.

[0119] Vehicle Motion Detection

[0120] The especially-preferred control system contains circuits thatdetect, amplify, and then validate signals electrical signals that aregenerated by various means when the vehicle is moving.

[0121] Once the system has validated the input signal, a “over-ride”signal is generated by the motion detection circuits and is routed tothe sensor validate circuit, which blocks any of the other sensor fromapplying and locking the brakes. Once this motion over-ride signal ispresent, the only means of over-riding its lock out of setting thebrakes is the use of the operators manual release switch, or of course,the vehicle coming to a halt.

[0122] There are two validation circuits used in this section of thecontroller unit. First, the signal must be present, uninterrupted, forapproximately 1 to 2 seconds before it qualifies as a legitimate signal.This limits the possibility of the brakes being set by short durationnoise picked up from the vehicle.

[0123] In addition to this 1 to 2 seconds validation time, the signalmust be of sufficient amplitude to cause the circuits non-invertingamplifier to rise above a trip point that is adjusted to be slightlyabove vehicle ground potential.

[0124] An example of an electrical signal that may be generated when thevehicle is moving is a magnetic pulse generator that may drive avehicle's electrically operated speedometer. In such an embodiment, thecontroller senses the output of the transmission pulse generator whenthe vehicle is in motion, without causing error in the vehiclespeedometer. Preferably, this vehicle-motion monitoring system isdesigned to sense the rotational speed of the transmission output shaft,and any rotation greater than a desired value overrides the applicationof the brakes except when the brakes are applied by the manualoperator's “activate/deactivate” switch. The vehicle-motion monitoringsystem is preferably compatible with either non-grounded or groundedspeedometer systems. An option for some vehicles is to provide afour-wire motion detection sensor, as opposed to a two-wire sensor, forthe speedometer pickup circuitry. This four-wire option may assuregreater accuracy of the speedometer and, therefore, the motion over-ridesystem of the invention.

[0125] The threshold of speed above which the controller will not applythe brakes may be set differently for different vehicles and locations.For example, a threshold in the range of about 5-10 miles per hour maybe desirable for passenger vehicles, while a threshold in the range ofabout 2-5 miles per hour may be desirable for school busses, forexample.

[0126] Other signals from the vehicle may be used for signaling thecontroller that the vehicle is in motion. For example, the controllermay be adapted to respond to Hall Effect, optical, infra-red, or othersignals that are generated by and sent to the speedometer via avehicle's primary computer system.

[0127] Power Supply and Input Line Noise Suppression and Protection

[0128] The input power to the unit from the vehicle +12 vdc electricalsystem is passed through both a common mode inductive/capacitive filter,as well as transient protection devices limiting the input voltagespikes to 18 volts maximum.

[0129] The controller logic section is somewhat electrically isolatedfrom the power required to run the brake solenoid valve by the use of anisolation diode. This is further supported by a number of various valuesof electrolytic capacitors connected between the +12 v reference voltageand ground at strategic points in the circuits.

[0130] The integrated circuit input lines from the off-board sensorshave both diode and resistive protection in accordance to manufacturesrecommendations for them. This same protection scheme is also employedon the input lines from the operators manual control switches.

[0131] Thus, the controller is designed to suppress and/or eliminatemomentary voltage excursions, both within and exceeding the normalpositive and negative limits of the primary operating power source, thatcan cause damage and/or improper operation of any electronics circuitsattached to the primary operating system.

[0132] Manual Control Functions

[0133] The manual control assembly contains two color coded push buttonswitches and two correspondingly colored light omitting diodes (LEDs)which provide the operator a visual indication of what state the airbrakes are in, preferably, green for released and red for locked.

[0134] The two switches, when active, place +12 v Ref (the workingprotected voltage for the controller, not raw vehicle +12 v) on theinputs to the two latches that either release or lock the brakes. Boththe release and the lock inputs have an 11 ms validation time to preventshort duration positive noise spikes from releasing the brakes.

[0135] Automatic Audio Device Cut-Off

[0136] The controller optionally provides logic and output line tooperate an exterior relay that may cut power to any sound-producingequipment whose power source is routed through it. This radio-cuttingfeature is restricted to the two different polarity door sensor inputlines as this function is demanded only when the passenger entry-exitdoor is opened, for example, for listening for trains or traffic.

[0137] The controller contains provision on the negative and thepositive door sensor circuits to power both an external optional relayand a corresponding indicator LED. When this option is used, activationof this relay by either of these two sensor input lines will breakoperating power to any audio device that is connected through it tovehicle +12 v.

[0138] Physical Size

[0139] The size of the solenoid, operator switch, and solid-statecontroller preferably are each less than 10″×5″×5″, and maybe any sizeneeded for a particular vehicle. Optionally, the controller may be madesmall enough, by microprocessor technology, to fit inside the operatorswitch.

[0140] ABS Compatibility

[0141] The solid-state control system includes a two-way check valvebetween the air supply and the solenoid valve, for compliance with ABSrequirements resulting from the use of a primary air source and asecondary air source. The check valve, or “shuttle valve,” may beincluded in the invented control system, for replacement of the loadingvalve in vehicles in which the conventional air loading valve wasdesigned in the past to include the check valve. For vehicles in whichthe check valve remains as apparatus separate from the conventional airloading valve, then removal of the loading valve and replacement by theinvented control system does not require the control system to include acheck valve.

[0142] Control Unit Connections

[0143] Connections to and from the control unit electronics assembly arepreferably standard automotive connectors as designated by the vehiclemanufacturer. Preferably, the control input lines are to be contained onone connector, while the other connector serves for the output lines tovarious LED lamps and for the +12 v DC and ground connections to powerthe electronics. Note that alternative embodiments may be adapted toother than 12 volt systems, or as customer-preferred.

[0144] Provisions have been made on the “input” side connector for asource 12 v battery and ground, so if at sometime an input interfacerequires power, it will be available. These two connectors will be ofdifferent genders so as to provide protection from unintentional mix upduring installation.

[0145] Auxiliary Input and Output Lines

[0146] Optionally, the control system may be designed to accommodate asmany additional inputs as is practical with regards to its impact onprinted circuit size and cost. Alternative embodiments, especiallymicro-chip technology, may include many data ports, including paralleland serial ports.

[0147] Auxiliary input lines preferably will respond to inputs that areeither switched to ground or to +12 v of the vehicle electrical system.Preferably, if some type of vehicle sensor is employed that does notprovide switching to either ground or +12 v of the vehicle electricalsystem, the conversion to this type switching will have to take placeexterior to the designed control circuit, ie. via addition of a switch.

[0148] Operating Voltage and Current Handling Limitations

[0149] Nominal operating voltage for the preferred system is 10.8 to13.8 volts direct current. Preferably, the solenoid output leads arelimited to de current loads, ground sourced, of not less than 18 ohmscontinuous operation at a direct current voltage of not more than 13.8volts. In the especially-preferred embodiment, the maximum allowableauxiliary power connections are limited to not more than 0.5 amps at13.8 amps with the brake solenoid energized.

[0150] Transient Protection

[0151] Transient and over-voltage protection of the circuit may beprovided by the strategic placement of various chokes, transientsuppresser diodes, filter capacitors, diodes and surge protectors, aswould be found necessary and appropriate in view of accepted adequatedesign practices, once the disclosure of this Description if viewed byone of skill in the art.

[0152] Battery Connection Reversal Protection

[0153] A 3 amp 200 v diode will be provided in series with the main +12v battery connections to the unit.

[0154] Internal and External Fusing

[0155] Operating instructions for the unit will require the use of anexternal fuse of a maximum amperage rating of 2 amps at 32 volts DC.Internal to the unit, and connected in series with the drain of the passelement transistor, shall be another fuse, rated at 3 amps at 32 voltsD.C.

[0156] Operating Temperature Range

[0157] The desired operating temperature window of the brake controlsystem is from approximately 32 degrees Fahrenheit to approximately 125degrees Fahrenheit.

[0158] Schematics of Solid-State Embodiment Logic and Wiring

[0159] The logic and functions of one solid-state embodiment areportrayed in FIGS. 12 and 13. The controller preferably has burned-inmemory so that, when the vehicle engine is off and, therefore, theignition system does not provide power to the invented unit, batterypower is not needed to maintain the memory in the controller and thecontrol system does not drain the vehicle's battery.

[0160] Although this invention has been described above with referenceto particular means, materials and embodiments, it is to be understoodthat the invention is not limited to these disclosed particulars, butextends instead to all equivalents within the scope of the followingclaims.

We claim:
 1. In a vehicle comprising a motorized vehicle with a driver'scab and a towed vehicle being pulled by the motorized vehicle and havinga parking brake, a brake control system comprising a controller systemand a management system, the controller system comprising: sensorslocated on or near the vehicle comprising sensors that are located onthe towed vehicle; an electronic controller located in the driver's cabadapted to receive signals from a plurality of sensors that signalconditions unsafe for vehicle movement on or near the vehicle, thecontroller adapted to command the management system to apply the parkingbrake when one or more of said sensors signal unsafe conditions; anelectronic operator switch located in the vehicle cab and accessible toa driver of the vehicle, the operator switch having an apply-brakeposition and a release-brake position and operatively connected to thecontroller to communicate apply-brake and release-brake commands to themanagement system via the controller; and the management system locatedin the towed vehicle comprising means for applying the parking brake inresponse to apply-brake signals from the controller and for releasingthe parking brake in response to release-brake signals from thecontroller; wherein said sensors on the towed vehicle signal thecontroller by means selected form the group consisting of electricalconnections, electronic connections, data connections, fiber optics,wireless transmissions, and combinations thereof; wherein the controllercommunicates with the management system by means selected from the groupconsisting of electrical connections, electronic connections, dataconnections, fiber optics, wireless transmissions, and combinationsthereof; wherein the motorized vehicle does not have a hand or footoperated parking brake handle in the cab that is mechanically linked tothe parking brake.
 2. The brake control system of claim 1, wherein theparking brake is a spring-operated air parking brake and the managementsystem comprises a solenoid air valve at or near wheels of the towedvehicle and air lines to and from the solenoid air valve that do notextend to the motorized vehicle.
 3. The brake control system of claim 1,wherein the parking brake is a hydraulic parking brake and themanagement system comprises a hydraulic cylinder at or near the towedvehicle wheels and hydraulic lines from the hydraulic cylinder that donot extend to the motorized vehicle.
 4. The brake control system ofclaim 2, wherein said air lines are each less than 5 feet long.
 5. Thebrake control system of claim 3, wherein said hydraulic lines are eachless than 5 feet long.
 6. The brake control system of claim 1, whereinthe controller system is adapted so that, when the parking brake hasbeen applied by the management system due to the controller sending anapply-brake commend to the management in response to unsafe signals fromone or more sensors, the apply-brake command is overridden when the saidoperator switch is manually held in the release-brake position by thedriver's hand while the vehicle is driven to safety.
 7. The brakecontrol system of claim 1, wherein said sensors on the towed vehiclesignal the controller by wireless communication and the controllercommands the management by wireless communication so that the vehicledoes not comprise a wired connection between the motorized vehicle andthe towed vehicle for parking brake operation.
 8. The brake controlsystem of claim 1, wherein the controller further comprises a validationcircuit that validates each unsafe signal from the plurality of sensorsby requiring that the unsafe signal continue uninterrupted for at leasta minimum amount of time before the controller reacts to the validatedsignal to command the management system to apply the parking brake. 9.The brake control system of claim 8, where said minimum amount of timeis in the range of 0.5 to 2 seconds.
 10. The brake control system ofclaim 1, wherein the operator switch is a push-button switch comprisingtwo separate buttons that are an apply-brake button and a release-brakebutton.
 11. The brake control system of claim 1, wherein the controllersystem is adapted so that the driver moving the operator switch to theapply-brake position causes the controller to command the managementsystem to apply the parking brake even if no unsafe signals are beingsent to the controller from said signals.
 12. The brake control systemof claim 1, wherein the controller system is adapted so that the drivermoving the operator switch to the release-brake position causes thecontroller to command the management system to release the parking brakeonly if no unsafe signals are being sent to the controller from saidsignals.
 13. The brake control system of claim 1, wherein, when saidunsafe signals to the controller cause the parking brake to be applied,the controller system is adapted to be overridden to release the parkingbrake by the driver continuously applying pressure on the operatorswitch in the release-brake position, so that the driver may drive thevehicle until the driver releases the pressure on the operator switch.14. The brake control system of claim 1, wherein one of said sensorssignaling the controller to apply the parking brake is a traintransmitting a signal that is receivable by the controller when thevehicle is within less than 50 feet of the train.
 15. The brake controlsystem of claim 1, wherein one of said sensors signaling the controlleris a train transmitting a signal that is receivable by the controllerwhen the vehicle is within less than 10 feet of the train.
 16. The brakecontrol system of claim 1, wherein one of said sensors signaling thecontroller comprises the transmission system signaling the controllerthat the transmission is being put in a park condition, wherein thecontroller responds to the transmission system signal by commanding themanagement system to apply the parking brake.
 17. The brake controlsystem of claim 16, wherein the controller commands the managementsystem to apply the brake in response to the transmission system signaland the management system applies the parking brake before a pawl of thetransmission system moves into its park position in the transmission 18.The brake control system of claim 17, wherein the parking brake isapplied less within 1 second of the pawl moving into the park position.